cratefield-i18n

Server-side localisation for a Cratefield venture: Project Fluent catalogs, BCP 47 negotiation, and the text direction unic-langid does not carry.

Nothing in it is notification-specific. A Catalog answers "render message booking-confirmed, attribute .title, in id-ID"; what the caller does with the answer is the caller's business.

use cratefield_i18n::{Args, FluentCatalog, TITLE, localize};

let catalog = FluentCatalog::builder()
    .default_locale("en")
    .locale("en", include_str!("../locales/en.ftl"))
    .locale("id", include_str!("../locales/id.ftl"))
    .build()?;

let rendered = localize(&catalog, &"id-ID".parse()?, "booking-confirmed", TITLE, &Args::new());
assert_eq!(rendered.text, "Pesanan dikonfirmasi");
# Ok::<(), Box<dyn std::error::Error>>(())

include_str!, not a file read: a Worker isolate has no filesystem, and a catalog built at cold start from data already in the binary costs one parse per isolate.

Three things it exists to get right

It is Send + Sync. The FluentBundle every example uses is built on Rc/RefCell and is neither. SendWrapper does not fix that — it grants Send alone and panics if the value is dropped off-thread. This crate uses the concurrent memoizer and a static assertion pins it, so undoing that is a compile error.

Direction is an explicit list. unic-langid parses tags and carries no directionality data at all. direction() answers from a script list (Arab, Hebr, Thaa, Nkoo, Adlm) and a language list (ar, he, fa, ur, ps, sd, yi, dv, ckb), script first, and is tested both ways.

A missing key is visible. localize falls back per message — a half-translated locale stays useful — and when no locale has the key at all it renders the key itself and says so. An empty body looks delivered; booking-confirmed.body is a bug report that names what to add.

missing_messages() is the same question asked before a deployment sends anything, and it lists identifiers only.

What a caller must not do

Argument values are personal data — a name, a place, a booking reference — so a rendered string is too. Nothing here puts one in an error, and a caller must keep it out of logs, events and columns as well.

MIT. Built in the open for Cratefield, a Factory Zero venture.